1. Field
Aspects of embodiments according to the present invention relate generally to an organic light emitting diode (OLED) display.
2. Description of Related Art
An organic light emitting diode (OLED) display includes organic light emitting elements each formed of a hole injection electrode, an organic emission layer, and an electron injection electrode. With the OLED display, electrons and holes are combined with each other in the organic emission layer to thereby generate excitons. When the excitons shift from the excited state to the ground state, energy is released so as to emit light, and images are displayed on the basis of the emitted light.
An OLED display is a flat panel display that can be made lightweight and thin because the OLED display has a self-luminous characteristic and requires no separate light source. Particularly, the OLED display exhibits desirable quality characteristics such as low power consumption, high luminance, and high response speed. Therefore, the OLED display is regarded as a next-generation display device.
The organic light emitting element may deteriorate due to internal and external factors. Of the internal factors, the organic emissive layer deteriorates because of oxygen from indium tin oxide (ITO) that is used as the electrode material, or under an interfacial reaction between organic layer components of the organic emissive layer. The external factors include external moisture and oxygen, and ultraviolet rays. In particular, as the external oxygen and moisture seriously influence the life span of the organic light emitting diode, it is very important to package the organic light emitting diode such that it is sealed from the outside in a vacuum-tight manner.
A thin film encapsulation (TFE) technique may be applied in packaging the organic light emitting diode, which is well known to those skilled in the art. With the thin film encapsulation technique, one or more of inorganic and organic layers are alternately deposited on the organic light emitting elements formed at the display area of the substrate, thereby covering the display area with a thin film encapsulation layer. In an OLED display with such a thin film encapsulation layer, if the substrate is formed with a flexible film, it can be bent easily, and a slim structure may be formed.
However, the flexible organic light emitting diode (OLED) display has a structure in which a plurality of inorganic layers and a plurality of organic layers are alternately deposited such that an optical characteristic in terms of a viewing angle is changed. To compensate for the change of the viewing angle, a viewing angle compensation film including a plurality of phase difference films, a prism sheet, or beads may be used. However, the viewing angle compensation method uses a plurality of phase difference films such that the thickness of the organic light emitting diode (OLED) display is increased, and the manufacturing process is complicated such that cost is increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.